title: PI3K/mTOR pathway inhibitors sensitize chronic myeloid leukemia stem cells to nilotinib and restore the response of progenitors to nilotinib in the presence of stem cell factor.
abstract: Nilotinib is a second-generation tyrosine kinase inhibitor, designed to specifically inhibit break-point cluster region (BCR)-Abelson (ABL) and developed to treat chronic myeloid leukemia (CML) in patients showing a resistance to imatinib. We previously demonstrated that nilotinib-induced apoptosis was reduced by stem cell factor (SCF) addition. Here, the SCF-activated survival pathway was investigated. BCR-ABL expression was accompanied by the activation of the SCF receptor: c-KIT. Nilotinib inhibited this activation that was restored by SCF binding. Parallel variations were observed for mammaliam target of rapamycin (mTOR) kinase and mTOR complex 1 substrate S6K. The inhibition of mTORC1 restored the response of BCR-ABL cell lines to nilotinib in the presence of SCF. PI3K inhibition restored nilotinib-induced apoptosis. On hematopoietic progenitors from CML patient's bone marrows, mTORC1 inhibition also restored nilotinib sensitivity in the presence of SCF, confirming its involvement in SCF-activated survival pathway. However, this pathway seems not to be involved in the nilotinib-induced resistance of the CML stem cell population. Conversely, PI3K inhibition sensitized both CML progenitors and stem cells to nilotinib, suggesting that, downstream PI3K, two different kinase pathways are activated in CML progenitor and stem cell populations.
authors.affiliation: 1] Laboratoire d'Hématopoïèse Leucémique et Cibles Thérapeutiques, INSERM 1035, Université Bordeaux Segalen, 146 Rue Léo Saignat, Bordeaux Cedex 33076, France [2] CHU Bordeaux, Hôpital Haut-Lévêque, Laboratoire d'Hématologie, Avenue Magellan 33604 Pessac, France.
authors.forename: K
authors.initials: K
authors.lastname: Airiau
authors.forename: F-X
authors.initials: FX
authors.lastname: Mahon
authors.forename: M
authors.initials: M
authors.lastname: Josselin
authors.forename: M
authors.initials: M
authors.lastname: Jeanneteau
authors.forename: F
authors.initials: F
authors.lastname: Belloc
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000473:pathology; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology*; D008954:Models, Biological; D014411:Neoplastic Stem Cells / Q000473:pathology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D019089:Stem Cell Factor / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D016044:Fusion Proteins, bcr-abl; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D019000:Phosphotyrosine; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011743:Pyrimidines; D019089:Stem Cell Factor; D058570:TOR Serine-Threonine Kinases; C498826:nilotinib